Overhead loader yoke mechanism



Aug. 8, 1950 L. R. THORNE 7 2,518,096

OVERHEAD LOADER YOKE MECHANISM Filed Dec. 13, 1947 3 Sheets-Sheet 1 INVENTOF? R. THORNE OVERHEAD LOADER YOKE MECHANISM Aug. 8, 1950 Filed Dec. 15, 1947 3 Sheets-Sheet 2 FIG. 2

Aug. 8,1950 R. THORNE OVERHEAD LOADER YOKE MECHANISM 5 Sheets- Sheet 5 Filed Dec. 13, 1947 Patented Aug. 8, 1950 Theme, Edmonton, Alberta,

" Canada natal... "Deee beris, 194m, .SerialNo. $791540 I In Canada'Decemher.23,.1946

em-1h. (01. 214-131) Overhead loaders .areiused rfor iithe purpose of loading or moving earth, gravel, sand, snow or other material from a position in front of a tractor or other motive-powered machine to a position immediately behind the machine. This is accomplished by means of hydraulic cylinders or drums and cables.

Hydraulically operated overhead loaders now in use have several disadvantages. In order to lift the shovel or scoop high enough to clear the cab of the tractor or other motive-powered machine to which the overhead loader is attached, it is necessary to place the bucket orscoop a considerable distance ahead of the machine on the end of a long boom. This disposition of the load gives a mechanical disadvantage which causes an unnecessary amount of power to be used in transferring the loaded bucket from the digging position in front of the machine to the unloading position behind it.

The second disadvantage is caused by poor leverage obtained in present type machines at the critical point at which the loader is starting to shift the load vertically from the digging position. This is because the cylinder exerting the force is operating at an acute angle to the boom holding the shovel. Most of this force is wasted. The peak pressures needed at this point often result in a break-down of the machine.

To overcome the first difliculty, I have reduced the length of the boom needed to clear the motive-powered machine. This not only increases the mechanical advantage of the machine but cuts down the unproductive weight represented by the additional length. I have also solved the second problem by allowing the hydraulic rams more eflicient leverage at all times in handling the load.

Figure 1 of the attached drawings illustrates my invention in the digging position.

Figure 2 shows the mechanism in the lifting .position.

Figure 3 shows the shovel in the dumping position.

Returning to Figure 1. suitable side frames F, F are attached to each side of the motive-powered machine. Pivotally mounted at D on each side of the machine is a link member A. The U-shaped frame or yoke B is connected to the link members at E, the base of the U crossing in front of the motive-powered machine. The after ends of the yoke B are bent in a vertical plane as indicated in the diagram. A suitable shovel or scoop C is attached to the cross-wise section of the U-shaped yoke B.

A master cylinder jM is pivotally mounted on the side frame 'F at the point G, a wide angle of swing being achieved by the use of trunnion T. The other end of the master hydraulic ram bears against the connection between the link A and the yoke B at the pivotal bearing point E. The secondary cylinder S is pivotally attached to the main bearing at D. The end of the secondary hydraulic ram is pivotally attached at a suitable point along the diagonal portion of the U-shaped yoke B at H.

In Figure 1 both hydraulic rams are fully retracted. In Figure 2 the master hydraulic ram is almost fully extended and the secondary ram is slightly extended.

In Figure 3 both hydraulic rams are almost fully extended and the shovel has reached a point behind the motive-powered machine.

To raise the load from the digging position, the master cylinder M, pressing against the pivotal point E, pivots the yoke B about the point D by means of the leverage exerted on the link A. At this stage in the operation the ram of the secondary cylinder S extends at a slower rate, exerting its pressure on the pivotal connection at H, thus pivoting the yoke B about the point E. It also serves to maintain a rigid connection between the link A and the yoke B.

As the shovel reaches the lifting position and the ram of the master cylinder M becomes almost fully extended, the ram of the secondary cylinder S finishes its travel, continuing to pivot the yoke B about the point E. The secondary cylinder S thus assists in raising the load and also has the effect of swinging the shovel C a greater distance from the pivotal point D. This allows the shovel C sufii-cient clearance to pass over the cab of the motive-powered machine.

When the shovel C is in the dumping position. both rams will be fully extended. The link A and the bent portion of the yoke B will now be almost in the same straight line due to the extension of the ram of the secondary cylinder S.

It will be noted that the master cylinder M, is at all times exerting a force at a wide angle to the link A. This allows an emcient use of the power of the master cylinder M.

It will also be noticed that the shovel C need only be far enough ahead in the digging position to clear the front of the motive-powered machine. In spite of this it can well be raised high enough to clear the cab of the machine and reach a suitable elevation for dumping. This shortening of the distance from the pivotal point to the load means a decrease in power needed to raise the load from the digging position.

An additional and important advantage of the invention in question is that all the hydraulic cylinders are exerting their forces from dead pivotal points. In other words, each hydraulic cylinder is working from the frame of the motivepoweredmachine itself, so that at no time will one cylinder be working against the other instead of assisting it.

I claim:

An improvement to overhead shovel loader mechanisms comprising, linked members pivotally mounted on both sides of the vehicle; a yoke attachment consisting of a substantially horizontal section and a, diagonal section, both sections being in the same vertical plane, such yoke attachment pivotally connected to the end of the link members remote from the pivotal mounting thereof; double acting hydraulic cylinder means reactable between the pivotal mounting of the link members and the diagonal portion of the yoke attachment; additional double acting hydraulic cylinder means pivotally mounted on the said vehicle and reactable between the said vehicle and the pivotal connection of the yoke attachment and the link member; an implement operatively mounted to. the crosswise portion of h l e d y k e ti i nt LEONARD RAYMOND THORNE.

V REFERENCES CITED The following references are of record in the me of this patent? 

